A variety of hand tools of the type comprising a reciprocating jaw wrench have been proposed heretofore. All have as their intended function means for gripping and holding nuts or bolts of more than a single size. These wrenches usually control the opening and closing of the jaws by means of either a traveling and rotating screw, or a cam mechanism, or a toggle linkage arrangement. The more simple of these, such as that shown and described in U.S. Pat. No. 3,625,096, comprise a stationary handle and a slidable jaw assembly having a frictional locking arrangement for maintaining a desired jaw opening. Other devices intended to accomplish a generally similar function comprise an adjustable jaw wrench which includes a toggle locking arrangement for locking the opposing jaws onto a bolt (or nut). This type of device is shown and described in U.S. Pat. Nos. 2,536,463 and 3,564,956. A similar toggle mechanism is shown in the hand tool described in U.S. Pat. No. 372,080. While each of the foregoing devices of the prior art have one or more advantageous features, they have not met with widespread economic success due to some particular shortcoming or limitation. For example, various of these prior devices are considered to be unsatisfactory because of their inability to quickly engage and thereafter quickly disengage the object to be gripped, yet be readily adjustable to accommodate a range of object sizes. It will be recognized that there may be other objections to various prior devices with respect to their ability to match the angle of the bolt faces to be gripped.